Valve-grinding compound



Patented May 15, 1928.

UNITED STATES PATENT OFFICE.

AI BTHUR LEE BRO'WNE, OF BALTIMORE, MARYLAND, ASSIGNOR TO THE AMERICANHAMMERED PISTON RING COMPANY, OF BALTIMORE, MARYLAND, A CORPORA- TION OFMARYLAND.

Io Drawing.

articles being ground; and therefore, it is.

necessary to finish grind, or lap, with a finer grade of abrasive. Toobtain the proper finish on the surface being ground, when using agrease-mixed compound, it is necessary, therefore, first to use a coarsegrade of abrasive for the cutting operation, and to finish with a finegrade to obtain a polish.

(b) It is diflicult to clean the surfaces that have been lapped orground, with a greasemixed compound, and particularly is this true. whengrinding the valve seats in automobiles. Inability to clean the valveseats perfectly in an automobile after grinding, naturally causes veryserious results, as the emery, carborundum, or other abraslve used,

sooncauses wear, and should this abrasive 80 get down into the cylindersit would cause an untold amount of trouble due to cuttin action upon thepiston rings, piston an cylinder. Furthermore, a grease-mixed compoundis greatly afi'ected by cllmatic changes,

becoming .quite fluid in excessively hot weather, and extremely stiff invery cold weather.

. In view of the above disadvantages, the so-called water-mixed grindingcom ound has come into use in recent years, an particularly for grindingthe valves of automobiles. The water-mixed compound has the advantage ofallowing the use of a well graded mixture oflabrasive or carborundumgrit, which cuts quite rapidly at first, but owing to the frictionproduced by grinding, the particles soon break down into smallerparticles, which with the continued grinding action produce a highlypolished surface.

Consequently, with water-mixed compound it is not necessary to use twogrades of abrasive, but one medium grade or well propor- VALVE-GRINDINGCOMPOUND.

Application-filed August 29, 1927. Serial No. 216,846.

. tioned mixture of abrasive or carborundum grinding compound isthoroughly removed,

the article dried, and the final coating of oil applied. Consequently, agrinding com pound that will prevent the rapid formation of rust wouldbe a decided advantage to the industry. I

Secondly, the water-mixed com ounds have a tendency to dry out very rapiy, and it is necessary to keep the container holding the grindingcompound closed at all times, in order to prevent the grinding com oundfrom drying out to such an extent 1: at'it is useless unless it is againwell mixed with the additlon of water, and even then,*it is seldom asgood as was the original mixture.

The rapid drying action of the grinding compound necessitates frequentapplication of water to the article while grindlng, and this isobjectionable to the users.

Furthermore, with the water-mixed compound, there is, of course, thepossibilit of such compound freezing in very cold 0 imates. In some ofthese water-mixed compounds substances have been added to the compoundto prevent freezing, and also to lessen the tendency of these compoundsto dry, but it is well known in the tradethat none of these mixtureshave proved entirely satisfactory and all of the compounds now on themarket have a tendency to dry out very rapidly, which is'perhaps, theirmost serious disadvantage.

In the valve rinding compound to be now described and orming the presentinvention the chief difficulties with the water-mixed com oundsheretofore on the market, and as a ve set forth, are overcome, since thecompound will not cause the formation of rust but will actually preventrust, and furthermore, will not dry out or be affected by climaticconditions.

In the grinding compound of this inven tion, there is used a medium finegrade of abrasive, such as carborundum grade 180. w

This grade consists mainly of grit that will pass 180 mesh sieve, but italso contains a small amount of coarser particles as well as a smallamount of very line particles. It has been found thatby the use of thisgrade of abrasive a grinding compound can be produced which will cutquite rapidly at first but which eventually breaks down into a finerabrasive powder, during the grinding operation, and produces a highpolish.

The abrasive is mixed with a binder or vehicle consisting mainly ofglycerine and soap. The glycerine is first heated to a moderate heat forexample to 200 F., say

by placing the glycerine in a steam bath, and to the Warm glycerine acertain amount of soap is added. The soap can be common laundry soap,yellow or white in color, and

in the solid state as found on the market, or dried, if desired. Uponmixing, this produces a jellylike substance which acts as an idealbinder for the abrasive material. To prevent this binder from becomingtoo thin under the influence of heat a small amount of oleic or otherfatty acid is added, and after mixing the whole there is added a dilutesolution of silicate of soda (about 1 part of silicate of soda solution(waterglass) and 4 parts water). While oleic acid is here mentioned,other fatty acids such as palmitic or stearic can be used, in fact anyfatty acid which will combine with an alkali to form asoap.

This produces a soft jellylike binder unaffected by climatic conditions,and furthermore the composition will not dry out or cause the formationof rust. To this binder the abrasive is added. It will beunderstood thatwhile carborundum will be particularly referred to herein, various othersolid abrasive substances, as corundum, emery and others, may beemployed. When the binder and abrasive are mixed together the binder ispreferably heated to a moderate heat (say 140 F.), and held at thistemperature while the proper proportion of abrasive is added and thewhole thoroughly mixed. After cooling the grinding compound is readyforuse and can be packed in cans or other suit-' able containers convenientfor handling and marketing.

Without attempting to restrict the invention to any particular theory,it is believed that the oleic or other free fatty acid reacts with thesodium silicate to form a soap and a gel of silicic acid or silica gel.The silicic acid so formed is' thoroughly and intimately incorporatedwith the soap formed and that originally added, together with thewater'and glycerine, constitute the base or vehicle of the composition,giving the desired soft jellylike consistency, and aiding in holding thewater in the composition dur- Example 1.

Percent. Carborundnm 50 Glycerine 24 Soap .4. 4 Stearic acid 3 30%silicate of soda .4 Water 15 Example 93.

A grinding compound composed of the following ingredients, whichcompoundwill not be as stiff as the former:

Percent. Carborundum- 40 Glycerine 30 Soap 5 'Oleic acid 4 to 6 30-40%silicate of soda 3 to 5 Water 16 Example 3.

A particularly favorable formula, for

- making the product, is as follows 7 Per cent. Glycerine 30 oap 5O'leic acid m. 6 40% solution of silicate of soda 4 Water a; 1 15Carborundum 40 I claim 1. A paste-like abrasive material containing thereaction products of alkali metal silicate and a fatty acid togetherwith soap, water, glycerine and a solid finely divided abrasivematerial.

2. A paste-like abrasive material containing the reaction products ofsodium silicate and a fatty acid together with soap water, glycerine anda solid finely divide abrasive material.

3. A pasty abrasive material containing a pulverulent abrasive materialcarried in a vehicle containing silica gel and soap.

4. A pasty abrasive material containing Glycerine 30% ;'soap 5%- oleicacid 6%;

a pulverulent abrasive material carried in 40% solution of silicate ofsoda 4%; water 0 a vehicle containing silica gel and soap to- 15%; andcarborundum 40%. 1 gether with water and a substance capable Intestimony whereof I have signed my 5 of preventing rapid drying out ofthe water. name to this specification.

5. A pasty abrasive material consisting I essentially of thefollowing-ingredients: ARTHUR LEE BROWNE.

